An increment system for deuterium isotope effects on 13C chemical shifts of methylated benzenes

The complete series of all possible benzenes bearing one deuterium atom and one to five methyl groups was synthesized. The deuterium isotope effects on the carbon chemical shifts of the aromatic and aliphatic carbon atoms were measured and shown to obey an empirical increment system. The isotope effects over one bond correlate with the C,H spin coupling constants.